I hope you can help me. I recently purchased a house in Tampa, Florida with an ailing grapefruit tree in the back yard. According to my new neighbors, the previous owner did his best to kill the three and Im afraid he may have finally succeeded. The tree is an 80 to 100 year old Duncan Grapefruit with a trunk 46 in circumference. It is planted in a very sandy soil and is irrigated with well water rich in FeO2. There are multiple symptoms: The bark on of the base of the trunk is crackling and breaking off and where there is damage to the trunk sawdust is present In several locations, sap has oozed out and crystallized In locations where heartwood was exposed during pruning, there is extensive decay. The leaves are yellowing and dropping There is no new growth The set fruit (between .75 and 1.5 diameter) is dropping at a fairly constant rate. Some of the fruit yellows and then drops. Last month an ISA Arborist came out and addressed several of the problems: The bark issues were a result of a colony of ants. He used an insecticide for the ants and painted over the damaged bark. The rotting heartwood was because the previous owners placed bromeliads on the fresh wood keeping it moist. He filled the holes with a foam sealant and painted. The arborist did not address the crystallized sap and he was here while the tree was in a heavy bloom, prior to the leaves and fruit yellowing and dropping. I am think that the tree is getting enough water; the leaves do not curl. Also, last month I sprinkled a granular citrus fertilizer around the base (a good 5 around the trunk). What else can I do?
I suggest you post some photos of the entire tree and a photo or two showing the areas of concern. Older trees can go into a decline in which they do not pull out of on their own too well. With inherent disease and insect factors along with probable nutrient imbalances we may have too many issues working against us all at one time for this tree to overcome but as long as the tree is and has been sending out new growth we have a chance to help it along, in spite of the former owner of this tree. Old Duncans are hard to come by any more, at least out here. I'd hate to learn of a good old tree, which was an important bloodline of Citrus at one time, perishing without giving it a helping hand, whether we are successful in our quest or not. One quick question: are you saying the Iron oxide is in the water or is it in the soil only or is in both the water and the soil? Have you had the soil and water tested for hydrogen ion concentration and mineral content as those findings can really help us. Jim
I would guess that the iron in the water is iron sulfide (Fe+2) which is highly soluble in water and then oxidizes to iron oxide (Fe+3) in air. Iron oxide is practically insoluble in water. We see the iron oxide stains on buildings here where surface well water is used for irrigation as a result of this process.
I believe Iron oxide is a crystalline form. Several of our foothill and forest soils have Iron oxide in them giving them a reddish bronze colored profile. Some people call the accrued and accumulated rust, from old galvanized pipe, in the water holding tanks and in the water lines of the well water Iron oxide. I'd be more concerned over the amount of "locked up" or bound Iron in the soil. Sometimes in order to go back in and do some remedial treatment of older trees we should know what soil and water factors are working against us and which factors are working for us. I still believe much of our ground based fungal disease issues that can later move upward into the tree and cause damage are in part due to lack of air movement in the root zone. We do not see too many water mold issues or foot rot in Citrus from soils that have good aeration. Jim
Iron oxide (Fe2O3) is rust, and it is highly insoluble in water as are most of the Fe+3 forms of iron. Iron becomes soluble in water when it is reduced to Fe+2, a biotic process that often occurs in the absence of oxygen as iron is the next most efficient electron acceptor (compared to oxygen--Nitrate is next). The process revereses abiotically in the presence of air (oxygen). This process often results in a rust coating around the roots of wetland plants growing in muck soils due to the fact that they pump air into their roots.
if nothing else air layer the tree or get somone who knows how to graft. to graft a piece of the tree to a rootstock i would not graft it to any of you're other citrus in case there is some sort of disease. it may just be old and on its way out it happens especially if it was neglected. good luck